Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
  • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
  • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
  • H01S3/08—Construction or shape of optical resonators or components thereof
  • H01S3/086—One or more reflectors having variable properties or positions for initial adjustment of the resonator

Definitions

• the invention relates to an optical resonator for a laser, in particular for a CO2 laser, with two mutually opposing resonator mirrors which are arranged on the end, ground and optically polished end faces of a mirror carrier which is made of a material with a very low coefficient of thermal expansion, e.g. made of glass ceramic.
• An optical resonator of the type mentioned at the outset is e.g. known from DE-PS 31 51 228.
• the resonator mirrors are arranged on the end, ground and optically polished end faces of a glass-ceramic mirror carrier.
• these high demands on the accuracy of the resonator length L are very difficult to meet when grinding and optically polishing the end faces of a mirror carrier.
• the invention is therefore based on the object of achieving the most accurate, defined and reproducible possible adjustment of the mirror spacing L in an optical resonator of the type mentioned at the outset and with as little effort as possible.
• optical resonator of the type mentioned in accordance with the invention in that the mirror support is divided in a plane extending obliquely to the optical axis of the resonator, so that two support parts are formed which are mutually adjustable on the oblique contact surfaces facing each other .
• a mirror support consisting of two parts is provided with inclined adjustment surfaces provided between the support of the first mirror and the support of the second mirror.
• the two carrier parts can be displaced relative to one another on these wedge-like adjustment surfaces, so that the resonator length or the absolute mirror spacing L can be set very precisely in the smallest adjustment ranges.
• the adjustment surfaces between the Both parts of the mirror support can be produced in a simple manner by diagonally separating an initially one-piece mirror support or by inserting or adding a wedge to one end of a one-piece mirror support and by grinding and optically polishing the adjoining adjustment surfaces.
• the optical resonator according to the invention thus ensures, with very little effort and without additional aids, an extremely precise adjustment of the mirror spacing in the smallest adjustment ranges.
• the basic structure is common to both embodiments of an optical resonator according to FIGS. 1 and 2.
• the optical resonator consists of two mutually opposing resonator mirrors 1 and 2, which here are designed as plane parallel mirrors and are arranged directly on the end, ground and optically polished end faces 3 and 4 of a block-shaped mirror carrier 5 and 6, respectively.
• This consists of a material with a very low coefficient of thermal expansion, preferably of a glass-ceramic material.
• the glass ceramic known under the trademark "Zerodur” from Schott has proven to be particularly suitable as such material.
• the mirror support 5 or 6 each has a central recess 7 or 8 and end-side recesses 9 or 10 and contains a waveguide comprising an aluminum oxide tube 11, which in the embodiment according to FIG. 1 in between the central recess 7 and the end-side recesses 9 formed intermediate walls 12 is held, while the aluminum oxide tube 11 is held in the embodiment according to Figure 2 in a suitable manner, not shown.
• the embodiment shown in FIG. 1 with a wedge 5b is most expedient with regard to the waveguide holder.
• the resonator mirrors 1 and 2 consist of a CO2 laser, for example made of zinc selenide or germanium and are held in the simplest case by the negative pressure prevailing inside the mirror support 5, 6 on the end faces 3 and 4.
• the mirrors can already be adequately fixed.
• Such means can be, for example, wire clips pressing against the mirror.
• these means are only additional fasteners and have no adjusting effect.
• the mirror carrier 5 or 6 is divided in a plane running obliquely to the optical axis of the resonator.
• two carrier parts 5a, 5b and 6a, 6b are formed, which can be adjusted relative to one another on the mutually facing inclined support surfaces 13, 14 and 15, 16 in the direction of arrows 17 and 18a, 18b.
• the mirror spacing L and thus the resonator length can be adjusted very precisely by ⁇ L in the smallest adjustment ranges.
• Invar screws are suitable as adjustment means, the play of the adjustment screws being able to be compensated for by a wedge-type adjustment ratio which is small compared to the adjustment to be effected.
• the gear ratio can be, for example, about 1: 100 to. 1: 1000 can be selected.
• the maximum adjustment range .DELTA.L max can be approximately 10 .mu.m, which means a stroke of the second carrier part with respect to the first carrier part of 1 mm with a transmission ratio of 1: 100.
• the parting plane of the mirror support 5 is provided in the area of the right end of the mirror support. This results in a longer support part 5a and a smaller support part, which is formed by a narrow wedge 5b.
• the two resonator mirrors 1 and 2 are therefore not arranged on the mutually parallel end faces of a one-piece mirror support, but it is only the one mirror 1 directly on the end face 3 of the longer support part 5a of the mirror support, while the other mirror 2 is attached to the end outer end face 4 of the interposed wedge 5b.
• the outer end face 4 of the wedge 5b is parallel to the end face 3 of the longer carrier part 5a.
• the parting plane of the mirror carrier 5, which forms the two inclined support surfaces 13, 14, is preferably inclined at a very small angle to a plane running perpendicular to the optical axis of the resonator, in this case obliquely to the parallel end faces 3 and 4 of the mirror carrier 5 , wherein the angle of inclination ⁇ is between zero and a few arc seconds or arc minutes.
• the abutting, inclined support surfaces 13, 14 are ground and optically polished, so that exactly flat wedge surfaces are formed to adjust the wedge 5b against the carrier part 5a.
• the adjustment of the wedge 5b that is, the adjustment of the mirror spacing L and thus the adjustment of the resonator length to the wavelength of the laser radiation, is generally only required once, the adjustment optionally being able to be carried out in a guide that only allows a linear adjustment of the carrier parts against one another and a possible rotation of the carrier parts against each other is prevented.
• the mirror carrier 6 formed with two mutually parallel end faces 3 and 4 does not consist of a longer carrier part and a narrow wedge, but of two approximately equally large carrier parts 6a and 6b, ie the parting plane is located at the mirror carrier 6 about in the middle. Otherwise, the bearing surfaces 15 and 16 of the support parts 6a and 6b in terms of their further configuration (inclination, surface quality) like the support surfaces 13 and 14 in the embodiment according to FIG.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Optics & Photonics (AREA)
• Lasers (AREA)

Applications Claiming Priority (2)

Publications (3)

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ID=6303544

Family Applications (1)

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Cited By (1)

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• 1987
  • 1987-06-16 US US07/062,588 patent/US4847858A/en not_active Expired - Fee Related
  • 1987-06-22 DE DE8787108890T patent/DE3781726D1/de not_active Expired - Lifetime
  • 1987-06-22 EP EP87108890A patent/EP0251096B1/fr not_active Expired - Lifetime

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